Stopper for cutting tool

ABSTRACT

To provide a stopper for a cutting tool capable of getting a correct depth required in a medical treatment field, even if a few kinds of a cutting tool are available, without preparing a many cutting tools, the stopper for a cutting tool is fitted to a rotary shaft of a cutting tool having the rotary shaft, the stopper includes a locking member which has a through hole contacting to the rotary shaft of the cutting tool, a clamping member which is made of a shape memory material, provided at the inner and/or outer side of the locking member and can deform the locking member by its recovering force, and a cutout part reaching to the through hole from an outer peripheral edge thereof in the longitudinal direction of the rotary shaft.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a stopper for a cutting tool, which isused for a cutting tool such as a drill having a rotary shaft or a rootcanal cutting tool. The stopper is for restricting a cutting depth andmaking an idea of a cutting depth.

2. Description of the Conventional Art

As for a conventional dental prosthesis in a defective tooth, a methodusing a bridge and a method using a base denture have been generallydone. However, the method using a bridge includes the steps of cuttinghealthy natural teeth on both sides of a defective tooth to makeabutment teeth, engaging a metal body with the abutment teeth, andfixing the metal body, where the metal body is attached to a dentalprosthesis positioned at the defective tooth. Thus, engaging parts tomake abutment teeth should be provided, where these abutment teeth aremade by cutting healthy natural teeth. Further, since occlusal forceordinarily applied on a defective tooth is shared by abutment teeth,there is a problem that the life of natural teeth as abutment teeth islargely shortened. As for the method using a base denture, a dentalprosthesis is made by fixing an artificial tooth made of a resin orceramics on a base made of a synthetic resin. However, as for thismethod, the occlusal force applied on a dental prosthesis should beshared by remaining natural teeth and/or oral mucosae. Thus, there is anuncomfortable feeling while using a dental prosthesis, and taste of apatient becomes blunt because a denture base covers taste receptorsdispersed in an oral mucosal tissue. Further, there are important faultthat an alveolar ridge may be absorbed by using the denture base for along period of time.

As for a treatment method to solve such faults, a dental implanttechnique is developed. The dental implant technique includes the stepsof embedding an implant fixture as a maintaining and stabilizing devicefor a dental prosthesis into an embedding hole formed in a jawbone at adefective tooth, making the implant fixture to execute the function of adental root in a natural teeth, connecting and fixing a fixing devicefor a dental prosthesis at the oral cavity inner side of the implantfixture to make a dental prosthesis maintaining device, and fixing adental prosthesis to the dental prosthesis maintaining device.

In this implant treatment, it is important to correctly form a hole, inwhich a fixture is embedded, at a jawbone. Therefore, UnexaminedJapanese Patent Publication No. 2005-518834, for example, discloses amethod including the steps of taking a tomogram of a jawbone of a patentinto a computer, producing a surgical template, in which an embeddingdirection of a fixture is previously determined and a hole specifyingthe embedding direction of the fixture is formed based on data correctlysimulating complete states of a prosthesis including the fixture,attaching the surgical template into an oral cavity of a patient, andusing a drill corresponding to the direction of the hole formed in thesurgical template. At this time, a direction of the embedding hole isspecified with the surgical template and depth of the embedding hole isspecified with a flange shaped stopper integrally formed with a rotaryshaft of a cutting drill.

However, it is necessary to use a flanged cutting tool in order to carryout the above-described treatment. Thus, many dentists who own a cuttingtool having no stopper at a rotary shaft need to newly purchase acutting tool corresponding to various kinds of cutting depths.

SUMMARY OF TE INVENTION

An objective of the present invention is to provide a stopper for acutting tool by which a treatment using a surgical template can becarried out with a conventional cutting tool having no a stopper at arotary shaft.

Present inventors carried out earnest works to solve the above-describedproblems and, as a result, they found out the followings to complete thepresent invention. By supplying only a stopper separately from a cuttingtool, a treatment using a surgical template can be carried with aconventional cutting tool having no stopper at a rotary shaft. Further,they noted that a surgical cutting tool is certainly heated andsterilized before using it. When a shape memory material which recoversa shape at a temperature for heating and sterilizing is used for astopper for a cutting tool, the stopper for a cutting tool can bestrongly fixed to a rotary shaft of the cutting tool after heating andsterilizing it.

That is, an aspect of the present invention is a stopper for a cuttingtool to be fitted to a rotary shaft of a cutting tool having the rotaryshaft. The stopper includes a locking member which has a through holecontacting to the rotary shaft of the cutting tool, and a clampingmember which is made of a shape memory material, is provided at theinner and/or outer sides of the locking member and can deform thelocking member by its shape recovering force. The stopper furtherincludes a cutout part reaching to the through hole from an outerperipheral edge in the longitudinal direction of the rotary shaft.

A stopper for a cutting tool according to the present invention can makea conventional cutting tool having no stopper at a rotary shaft to carryout a treatment using a surgical template. Further, the stopper is anexcellent one which hardly cause positional shift even when using acutting drill or a dental root cutting tool.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view to illustrate a before heating state of oneexample of a stopper for a cutting tool according to the presentinvention.

FIG. 2 is a perspective view to illustrate one example of a cutting toolto which a stopper for a cutting tool is attached.

FIG. 3 is a perspective view to illustrate a state that the stopper fora cutting tool in FIG. 1 is temporarily attached to the cutting tool inFIG. 2.

FIG. 4 is a perspective view to illustrate a before heating state ofanother example of a stopper for a cutting tool according to the presentinvention.

FIG. 5 is a perspective view to illustrate an after heating state offurther another example of a stopper for a cutting tool according to thepresent invention attached to the cutting tool in FIG. 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

A stopper for a cutting tool according to the present invention will bedescribed below with reference to the drawings.

FIG. 1 is a perspective view to illustrate a before heating state of oneexample of a stopper for a cutting tool according to the presentinvention. FIG. 2 is a perspective view to illustrate one example of acutting tool to which a stopper for a cutting tool is attached. FIG. 3is a perspective view to illustrate a state that the stopper for acutting tool in FIG. 1 is temporarily attached to the cutting tool inFIG. 2. FIG. 4 is a perspective view to illustrate a before heatingstate of another example of a stopper for a cutting tool according tothe present invention. FIG. 5 is a perspective view to illustrate anafter heating state of further another example of a stopper for acutting tool according to the present invention attached to the cuttingtool in FIG. 2.

A stopper 1 for a cutting tool according to the present invention inFIG. 1 is, for example, fitted to a rotary shaft 2 a of a cutting tool 2illustrated in FIG. 2 and used. The cutting tool 2 is not limitedespecially if having a drill shape and including a rotary shaft, and thecutting tool 2 may have or may not have a cutting edge at the rotaryshaft.

The stopper 1 for a cutting tool according to the present inventionincludes a locking member 1 a having a through hole 1 aa contacting tothe rotary shaft 2 a, and includes a clamping member 1 b, which is madeof a shape memory material, provided at the inner and/or outer sides ofthe locking member 1 a, and can deform the locking member 1 a by itsshape recovering force. The stopper 1 further includes a cutout part 1ab reaching to the through hole 1 aa from an outer peripheral edge inthe longitudinal direction of the rotary shaft 2 a.

The locking member 1 a is used so as to surround the rotary shaft 2 a ofthe cutting tool 2. A shape of the locking member 1 a is not limitedespecially if having the through hole 1 aa contacting the rotary shaft 2a and having the cutout part 1 ab. As for a disk-shaped stopper for acutting tool illustrated in FIGS. 1, 3 and 4, the through hole 1 aahaving a slightly larger diameter than an outer diameter of the rotaryshaft 2 a is formed in the locking member 1 a.

The locking member 1 a is fitted to the rotary shaft 2 a by a clampingpart 2 described below. As for the stopper 1 for a cutting toolaccording to the present invention, the clamping member 1 b having ashape memory ability is recovered to clamp a rotary shaft by utilizingthe heat at a temperature for heating and sterilizing (about 130° C.).Thus, a material of the locking member 1 a is not limited especially ifsurrounding the rotary shaft 2 a of the cutting tool 2, for example,resin material or metal material. Preferably a flexible resin materialhaving high thermal resistance. For example, this material includespolypropylene, polycarbonate, polyarylate, polysulfone, polyphenylenesulfide, polyether etherketone, a polyimide resin, and a fluororesin.Particularly, polyamide imide and polyether etherketone are preferablebecause of having thermal resistance at 250° C. or more.

The clamping member 1 b is made of a shape memory material. Pluralnumbers of the clamping members 1 b may be provided inside the lockingmember 1 a as illustrated in FIG. 5. The clamping member 1 b may befitted and fixed on the outer side of the locking member 1 a so as tosurround the locking member 1 a as illustrated in FIGS. 1 and 3.Further, the clamping member 1 b may be fitted to a groove formed at anouter edge of the locking member 1 as illustrated in FIG. 4. In allcases, the clamping member 1 b is provided so as to surround the rotaryshaft 2 a.

The clamping member 1 b deforms the locking member 1 a by its shaperecovering force. The clamping member 1 b makes the stopper 1 for acutting tool fit to the rotary shaft 2 through the locking member 1, bybeing given a memory that a portion contacting a rotary shaft of thelocking member 1 a shrinks to be a smaller circle than the outerperiphery of the rotary shaft and recovering the portion to have theshape of the memory by heating at the time of sterilizing. The clampingmember 1 b is preferably a shape memory alloy having a shape recoveringtemperature of about 50 to 100° C.

A stopper for a cutting tool according to the present invention includesa cutout part 1 ab reaching to the through hole 1 aa from an outerperipheral edge thereof in the longitudinal direction of the rotaryshaft 2 a of the cutting tool 2. The locking member 1 a is deformed bythe shape recovering force of the clamping member 1 b so as to lose thecutout part 1 ab, and then the stopper for a cutting tool is fitted tothe rotary shaft 2 a. The cutout part 1 ab may be straight in thelongitudinal direction of the rotary shaft 2 a of the cutting tool 2 asillustrated FIGS. 1, and 3 to 5, may be inclined with respect to therotary shaft 2 a, may be in a crank shape, or may be in a wavy shape(these states are not illustrated).

One example of a stopper for a cutting tool according to the presentinvention is in a disk shape as illustrated in FIGS. 1 and 4. Thestopper includes a through hole 1 aa in a locking member 1 a, and acutout part 1 ab reaching to the through hole 1 aa. By this example, acutting depth of a cutting tool can be correctly got. Another example isa stopper for a cutting tool which is formed in a washer shape or a coilshape as the whole with using a locking member to surround the rotaryshaft 2 a and using a shape memory material on the outer side of thelocking member (this example is not illustrated).

Another example is a cylindrical stopper for a cutting tool including aflange part 1 c at one end, a through hole 1 aa, and a cutout part 1 abreaching to the through hole 1 aa, as illustrated in FIG. 5. In thiscase, the stopper can be certainly fitted to the rotary shaft 2 a of thecutting tool 2, and can get a correct cutting depth by the flange part 1c.

As for a using method of a stopper for a cutting tool according to thepresent invention, a stopper illustrated in FIGS. 1, or 3 to 5 is usedby the steps of previously expanding the cutout part 1 ab so as todeform it to have a sufficiently larger shape than the outer peripheryof the rotary shaft 2 a in order to easily attach the through hole 1 aaof the stopper 1 for a cutting tool to a predetermined position of therotary shaft 2 a, determining a depth of a cutting tool, deforming thecutout part 1 ab by an operator (closing the cutout part by the easiestway), temporarily fixing the stopper for a cutting tool to the rotaryshaft 2 a by using a pliers or a specific tool, and carrying out asterilizing treatment at a temperature of about 80 to 150° C. in aheating and sterilizing apparatus such as an autoclave or a dryness ovenaccording to an ordinary method before using the cutting tool. After thesterilizing treatment, since the stopper 1 for a cutting tool iscertainly fitted to the rotary shaft 2 a by the recovering force of theshape memory material 1 b, the position of the stopper is not easilyshifted at the time of using. After using the cutting tool, the stopperfor a cutting tool is removed from the rotary shaft by deforming by apliers or a specific tool, washed, and stored until the next time.

A stopper for a cutting tool according to the present invention can beused for a stopper conventionally used to restrict a cutting depth,e.g., a dental root canal cutting tool, in addition to a cutting drillfor an implant.

1. A stopper for a cutting tool to be fitted to a rotary shaft of acutting tool having the rotary shaft, the stopper comprising: a lockingmember which has a through hole contacting to the rotary shaft of thecutting tool; a clamping member which is made of a shape memorymaterial, is provided at on the inner and/or outer side of the lockingmember, and can deform the locking member by its shape recovering force;and a cutout part reaching to the through hole from an outer peripheraledge of the stopper in the longitudinal direction of the rotary shaft.2. The stopper for a cutting tool as claimed in claim 1, wherein thestopper is in an approximately disk shape.
 3. The stopper for a cuttingtool as claimed in claim 1, wherein the stopper is in an approximatelycylindrical shape having a flange at an end thereof.